Re: [PATCH v6 3/3] kselftest: mm: remove check_huge_shmem()

[Yeoreum Yun]

On Mon, Sep 14, 2026 at 04:16:40PM +0200, David Hildenbrand (Arm) wrote:
> On 9/14/26 09:30, Yeoreum Yun wrote:
> > check_huge_shmem() was required to distinguish shmem huge pages because
> > /proc/self/smaps reports them using a dedicated “ShmemPmdMapped” entry,
> > as opposed to “FilePmdMapped” for file-backed huge pages.
> > 
> > Now that /proc/self/smaps is no longer used to detect huge pages and
> > /proc/kpageflags is used instead, it is sufficient to distinguish
> > between file-backed and anonymous pages since the ShmemPmdMapped is also
> > kind of file-backed.
> > 
> > Therefore, remove check_huge_shmem() and use check_huge_file() instead.
> > 
> > Suggested-by: David Hildenbrand (Arm) <david@xxxxxxxxxx>
> > Signed-off-by: Yeoreum Yun <yeoreum.yun@xxxxxxx>
> > ---
> >  tools/testing/selftests/mm/folio_split_race_test.c |  2 +-
> >  tools/testing/selftests/mm/khugepaged.c            |  5 ++---
> >  tools/testing/selftests/mm/uffd-common.c           |  4 ++--
> >  tools/testing/selftests/mm/vm_util.c               | 11 +----------
> >  tools/testing/selftests/mm/vm_util.h               |  2 --
> >  5 files changed, 6 insertions(+), 18 deletions(-)
> > 
> > diff --git a/tools/testing/selftests/mm/folio_split_race_test.c b/tools/testing/selftests/mm/folio_split_race_test.c
> > index 1960635a953e..4c0d3b6a411b 100644
> > --- a/tools/testing/selftests/mm/folio_split_race_test.c
> > +++ b/tools/testing/selftests/mm/folio_split_race_test.c
> > @@ -182,7 +182,7 @@ static uint64_t run_iteration(void)
> >  	for (i = 0; i < TOTAL_PAGES; i++)
> >  		fill_page(mmap_base, i);
> >  
> > -	if (!check_huge_shmem(mmap_base, FILE_SIZE, NR_PMD_PAGE, pmd_pagesize))
> > +	if (!check_huge_file(mmap_base, FILE_SIZE, NR_PMD_PAGE, pmd_pagesize))
> >  		ksft_exit_fail_msg("No shmem THP is allocated\n");
> >  
> >  	if (pthread_barrier_init(&ctl.barrier, NULL, NUM_READER_THREADS + 1) != 0)
> > diff --git a/tools/testing/selftests/mm/khugepaged.c b/tools/testing/selftests/mm/khugepaged.c
> > index f82673f5f6b4..6cd1effea465 100644
> > --- a/tools/testing/selftests/mm/khugepaged.c
> > +++ b/tools/testing/selftests/mm/khugepaged.c
> > @@ -416,9 +416,8 @@ static bool file_check_huge(void *addr, size_t len, int nr_hpages,
> >  {
> >  	switch (finfo.type) {
> >  	case VMA_FILE:
> > -		return check_huge_file(addr, len, nr_hpages, hpage_size);
> >  	case VMA_SHMEM:
> > -		return check_huge_shmem(addr, len, nr_hpages, hpage_size);
> > +		return check_huge_file(addr, len, nr_hpages, hpage_size);
> >  	default:
> >  		ksft_exit_fail_msg("Unknown VMA type\n");
> >  		return false;
> 
> 
> Assuming we do:
> 
> diff --git a/tools/testing/selftests/mm/khugepaged.c b/tools/testing/selftests/mm/khugepaged.c
> index f82673f5f6b47..9542173a748e2 100644
> --- a/tools/testing/selftests/mm/khugepaged.c
> +++ b/tools/testing/selftests/mm/khugepaged.c
> @@ -53,7 +53,7 @@ struct mem_ops {
>         void *(*setup_area)(int nr_hpages);
>         void (*cleanup_area)(void *p, unsigned long size);
>         void (*fault)(void *p, unsigned long start, unsigned long end);
> -       bool (*check_huge)(void *addr, size_t len, int nr_hpages, unsigned long hpage_size);
> +       bool (*check_huge)(void *addr, size_t len, int nr_hpages, uint64_t hpage_size);
>         const char *name;
>  };
> 
> 
> Could we then simply use check_huge_anon/check_huge_file directly and get rid of
> these helpers anon_check_huge + check_huge_file entirely?

Yeap. I'll follow your suggetion. Thanks!

-- 
Sincerely,
Yeoreum Yun